MEMS-based waste vibration and acoustic energy harvesters

Abstract

Every machine vibrates and emits noise. This is unused energy that, with an appropriate mechanism, can be returned to the system. Utilizing an array of piezoelectric microelectromechanical systems (MEMS) devices to harvest this otherwise wasted energy, it is possible to improve the efficiency of any number of mechanical devices. Piezoelectricity is the mechanism by which certain crystalline structures generate electric potential when under strain, or, conversely, deform when subjected to an electric potential. It is this first effect that is important to this application. Though each MEMS device will generate a very small amount of power, a 1 m2 area can contain an array of millions of these devices. Energy harvesting, conservation, and efficiency are all key Department of Defense (DOD) priorities, and the universal application of these devices make them ideal for any expeditionary platform, such as ships, aircraft, and automobiles. This thesis designs and tests the first generations of acoustic and vibrational piezoelectric MEMS devices; including time-dependent finite element models, microfabrication processes, and the initial attempts at characterization and optimization.